/*
 * TokenMarker.java - Generic token marker
 * Copyright (C) 1998, 1999 Slava Pestov
 *
 * You may use and modify this package for any purpose. Redistribution is
 * permitted, in both source and binary form, provided that this notice
 * remains intact in all source distributions of this package.
 */
package com.pironet.tda.utils.jedit;

import javax.swing.text.Segment;
import java.util.*;

/**
 * A token marker that splits lines of text into tokens. Each token carries
 * a length field and an indentification tag that can be mapped to a color
 * for painting that token.<p>
 * <p>
 * For performance reasons, the linked list of tokens is reused after each
 * line is tokenized. Therefore, the return value of <code>markTokens</code>
 * should only be used for immediate painting. Notably, it cannot be
 * cached.
 *
 * @author Slava Pestov
 * @version $Id: TokenMarker.java,v 1.1 2007-10-03 12:50:26 irockel Exp $
 * @see org.gjt.sp.jedit.syntax.Token
 */
public abstract class TokenMarker {
    /**
     * A wrapper for the lower-level <code>markTokensImpl</code> method
     * that is called to split a line up into tokens.
     *
     * @param line      The line
     * @param lineIndex The line number
     */
    public Token markTokens(Segment line, int lineIndex) {
        if (lineIndex >= length) {
            throw new IllegalArgumentException("Tokenizing invalid line: "
                    + lineIndex);
        }

        lastToken = null;

        LineInfo info = lineInfo[lineIndex];
        LineInfo prev;
        if (lineIndex == 0)
            prev = null;
        else
            prev = lineInfo[lineIndex - 1];

        byte oldToken = info.token;
        byte token = markTokensImpl(prev == null ?
                Token.NULL : prev.token, line, lineIndex);

        info.token = token;

		/*
         * This is a foul hack. It stops nextLineRequested
		 * from being cleared if the same line is marked twice.
		 *
		 * Why is this necessary? It's all JEditTextArea's fault.
		 * When something is inserted into the text, firing a
		 * document event, the insertUpdate() method shifts the
		 * caret (if necessary) by the amount inserted.
		 *
		 * All caret movement is handled by the select() method,
		 * which eventually pipes the new position to scrollTo()
		 * and calls repaint().
		 *
		 * Note that at this point in time, the new line hasn't
		 * yet been painted; the caret is moved first.
		 *
		 * scrollTo() calls offsetToX(), which tokenizes the line
		 * unless it is being called on the last line painted
		 * (in which case it uses the text area's painter cached
		 * token list). What scrollTo() does next is irrelevant.
		 *
		 * After scrollTo() has done it's job, repaint() is
		 * called, and eventually we end up in paintLine(), whose
		 * job is to paint the changed line. It, too, calls
		 * markTokens().
		 *
		 * The problem was that if the line started a multiline
		 * token, the first markTokens() (done in offsetToX())
		 * would set nextLineRequested (because the line end
		 * token had changed) but the second would clear it
		 * (because the line was the same that time) and therefore
		 * paintLine() would never know that it needed to repaint
		 * subsequent lines.
		 *
		 * This bug took me ages to track down, that's why I wrote
		 * all the relevant info down so that others wouldn't
		 * duplicate it.
		 */
        if (!(lastLine == lineIndex && nextLineRequested))
            nextLineRequested = (oldToken != token);

        lastLine = lineIndex;

        addToken(0, Token.END);

        return firstToken;
    }

    /**
     * An abstract method that splits a line up into tokens. It
     * should parse the line, and call <code>addToken()</code> to
     * add syntax tokens to the token list. Then, it should return
     * the initial token type for the next line.<p>
     * <p>
     * For example if the current line contains the start of a
     * multiline comment that doesn't end on that line, this method
     * should return the comment token type so that it continues on
     * the next line.
     *
     * @param token     The initial token type for this line
     * @param line      The line to be tokenized
     * @param lineIndex The index of the line in the document,
     *                  starting at 0
     * @return The initial token type for the next line
     */
    protected abstract byte markTokensImpl(byte token, Segment line,
                                           int lineIndex);

    /**
     * Returns if the token marker supports tokens that span multiple
     * lines. If this is true, the object using this token marker is
     * required to pass all lines in the document to the
     * <code>markTokens()</code> method (in turn).<p>
     * <p>
     * The default implementation returns true; it should be overridden
     * to return false on simpler token markers for increased speed.
     */
    public boolean supportsMultilineTokens() {
        return true;
    }

    /**
     * Informs the token marker that lines have been inserted into
     * the document. This inserts a gap in the <code>lineInfo</code>
     * array.
     *
     * @param index The first line number
     * @param lines The number of lines
     */
    public void insertLines(int index, int lines) {
        if (lines <= 0)
            return;
        length += lines;
        ensureCapacity(length);
        int len = index + lines;
        System.arraycopy(lineInfo, index, lineInfo, len,
                lineInfo.length - len);

        for (int i = index + lines - 1; i >= index; i--) {
            lineInfo[i] = new LineInfo();
        }
    }

    /**
     * Informs the token marker that line have been deleted from
     * the document. This removes the lines in question from the
     * <code>lineInfo</code> array.
     *
     * @param index The first line number
     * @param lines The number of lines
     */
    public void deleteLines(int index, int lines) {
        if (lines <= 0)
            return;
        int len = index + lines;
        length -= lines;
        System.arraycopy(lineInfo, len, lineInfo,
                index, lineInfo.length - len);
    }

    /**
     * Returns the number of lines in this token marker.
     */
    public int getLineCount() {
        return length;
    }

    /**
     * Returns true if the next line should be repainted. This
     * will return true after a line has been tokenized that starts
     * a multiline token that continues onto the next line.
     */
    public boolean isNextLineRequested() {
        return nextLineRequested;
    }

    // protected members

    /**
     * The first token in the list. This should be used as the return
     * value from <code>markTokens()</code>.
     */
    protected Token firstToken;

    /**
     * The last token in the list. New tokens are added here.
     * This should be set to null before a new line is to be tokenized.
     */
    protected Token lastToken;

    /**
     * An array for storing information about lines. It is enlarged and
     * shrunk automatically by the <code>insertLines()</code> and
     * <code>deleteLines()</code> methods.
     */
    protected LineInfo[] lineInfo;

    /**
     * The number of lines in the model being tokenized. This can be
     * less than the length of the <code>lineInfo</code> array.
     */
    protected int length;

    /**
     * The last tokenized line.
     */
    protected int lastLine;

    /**
     * True if the next line should be painted.
     */
    protected boolean nextLineRequested;

    /**
     * Creates a new <code>TokenMarker</code>. This DOES NOT create
     * a lineInfo array; an initial call to <code>insertLines()</code>
     * does that.
     */
    protected TokenMarker() {
        lastLine = -1;
    }

    /**
     * Ensures that the <code>lineInfo</code> array can contain the
     * specified index. This enlarges it if necessary. No action is
     * taken if the array is large enough already.<p>
     * <p>
     * It should be unnecessary to call this under normal
     * circumstances; <code>insertLine()</code> should take care of
     * enlarging the line info array automatically.
     *
     * @param index The array index
     */
    protected void ensureCapacity(int index) {
        if (lineInfo == null)
            lineInfo = new LineInfo[index + 1];
        else if (lineInfo.length <= index) {
            LineInfo[] lineInfoN = new LineInfo[(index + 1) * 2];
            System.arraycopy(lineInfo, 0, lineInfoN, 0,
                    lineInfo.length);
            lineInfo = lineInfoN;
        }
    }

    /**
     * Adds a token to the token list.
     *
     * @param length The length of the token
     * @param id     The id of the token
     */
    protected void addToken(int length, byte id) {
        if (id >= Token.INTERNAL_FIRST && id <= Token.INTERNAL_LAST)
            throw new InternalError("Invalid id: " + id);

        if (length == 0 && id != Token.END)
            return;

        if (firstToken == null) {
            firstToken = new Token(length, id);
            lastToken = firstToken;
        } else if (lastToken == null) {
            lastToken = firstToken;
            firstToken.length = length;
            firstToken.id = id;
        } else if (lastToken.next == null) {
            lastToken.next = new Token(length, id);
            lastToken = lastToken.next;
        } else {
            lastToken = lastToken.next;
            lastToken.length = length;
            lastToken.id = id;
        }
    }

    /**
     * Inner class for storing information about tokenized lines.
     */
    public class LineInfo {
        /**
         * Creates a new LineInfo object with token = Token.NULL
         * and obj = null.
         */
        public LineInfo() {
        }

        /**
         * Creates a new LineInfo object with the specified
         * parameters.
         */
        public LineInfo(byte token, Object obj) {
            this.token = token;
            this.obj = obj;
        }

        /**
         * The id of the last token of the line.
         */
        public byte token;

        /**
         * This is for use by the token marker implementations
         * themselves. It can be used to store anything that
         * is an object and that needs to exist on a per-line
         * basis.
         */
        public Object obj;
    }
}
